Yes, it's an Easy Fear check (which they probably should have done before attacking).
I guess I don't see the point of pushing them into the hole and doing no damage if they can just get up again and attack me. So I'd rather "knock them prone" and see if I can reduce their numbers. 2 boost from Aim, then the boost you mentioned:
Do they taste like chicken? : 3eP+1eA+3eB+2eD 3 successes